Diode modulator



Oct. 26, 1948.

E. H- LANGE DIODE MODULATOR Filed June 26, 1944 IN VEN TOR.

ONQ

I I ll llllllll-i Q m k) N 3 L ll Patented Oct. 26, 1948 UNITED STATES--PATENT OFFICE DIODE MODULATOR Edward H. Lange, Baltimore, an.

Application June 26, 1944, Serial No. 542,181

. 21 Claims. 1

This invention pertains to thermionic diodemodulator devices foraccomplishing modulation of alternating currents in a variety ofessential control-networks for reception and transmission bf radiocommunication, by employment of impulse-excitation with predominantenergy storage or reactance facilities of such modulator circuits,together with modifications of negative biasvoltage upon one or morediode-anodes, and by employment of coupling between such diodemodulatorcircuits and control-networks, including thermionic amplifier coupling.Among the important uses of the diode-modulator devices of thisinvention are amplitude-modulation in thermionic alternating currentgenerators; limitation of alternating current amplitudes in suchgenerators to a range providing simple harmonic oscillations, and forimprovement of frequency stability together with single-frequencyphasebalancing of generator circuits; frequency-modulation in thermionicwave generators; limitation of amplitudes of alternating voltages to aconstant magnitude independent of amplitudes of impressed voltagesbeyond a selective threshold magnitude, in receivers forfrequency-modulated carrier waves; phase-regeneration infrequencydemodulators for receivers of frequency-modulated carrierwaves, for increasing the conversion sensitivity of such demodulators;automatic correction of tuning in superheterodyne receivers forfrequency modulated or amplitude modulated carrier waves; and for aWave-synthesizer, for evolving output-voltage waves of varying degreesof complexity from a simple harmonic inputvoltage wave, with a highdegree of selective control of the output-voltage amplitudes as to theirfunctional relationship tothe input-voltage amplitudes, and of phase andfrequency. These structures are hereinafter pointed out in furtherdetail, together with important features of this invention.

The principal object of this invention, is to provide a simplediode-modulation system having a high degree of utility in radiocommunication receiving and transmitting circuits, to efiect economiesin necessary electronic equipment heretofore required to provide some ofthe above-stated useful operations, and to provide a new and usefulsystem of phase-regeneration, and of amplitude, frequency, and phasecontrol in communication networks.

An object of this invention is to provide thermionic diode-modulatordevices, employing impulse excitation, together with predominant energystorage or reactance facilities "of the modulator circuit, and withmodifications of negative biasvoltage upon one or more diode-anodes, andcoupling between the modulator circuit and controlled network, includingthe use of thermionic amplifier coupling, for controlling alternatingcurrents of the controlled network, with a minimum of electronicequipment, and without the necessity of special thermionic tubes, or ofutilizing grid control elements to the exclusion of other simultaneoususes.

Another object of this invention, isto provide such modulator devicesfor effecting amplitudemodulation of alternating currents in athermionic alternating current generator; also to furnish a simple andselective control of the equilibrium currents of such alternatin currentgenerators, to confine such alternating currents to amplitudes yieldinga simple harmonic waveform, and to combine with these simple harmoniccurrents phase-balancing of generator networks, to attain stabilizationof the generated frequency.

Still another object is to furnishsimple means for accomplishingfrequency-modulation of the alternating currents of a thermionicalternating current generator, and to provide a new and useful system ofphase-regeneration in frequencydemodulator networks, for largelyaugmenting the conversion sensitivity of frequency-deviations intoo-utput-voltages; also to utilize the diodemodulators of this inventionto provide important tuning controls in superheterodyne receivers.

A further object, is to utilize the demodulator devices of thisinvention to provide a simple amplitude-limiter for use in receivers offrequency-modulated carrier currents, providing a selective control ofthe threshold magnitude of impressed alternating voltages, beyond whichoutput alternating voltages are maintained constant in amplitude,

Asixth object of this invention, is to furnish a new and usefuldiode-modulator device for the synthesis of waves, for evolvingoutputwoltage waves of varying deg-reesof complexity from a simpleharmonic inputevoltag-e wave, with selective control of incremental anddecremental outputvoltage amplitudes in relation to incremental inputvoltage amplitudes, and of phase and frcquency; also for providinginter-control of amplitudes, phase, and frequency in communicationnetworks.

These objects, and others, will be better understood by reference to theaccompanying drawings, and, to the following specification and appendedclaims.

In'the drawings,

Fig. 1 illustrates a thermionic alternating cur rent generator, with adiode-modulator of this invention, for introducing sinusoidaldegenerative voltages which are threshold determined by negativebias-voltage upon a diode-anode; also inductive coupling of thediode-modulator circuit with the generator network, for providingimpulse excitation of the demodulator circuit, and means for modulatingthe negative bias-voltage,

Fig. 2'shows a thermionic alternating current generator, with adouble-diode modulator device of this invention, employing impulseexcitation with substantially pure inductive reactance in the modulatorcircuit, and coupled with the generator network, and with amodulation-impedance for modulating the negative bias-voltage of thediode-anodes.

Fig. 3 illustrates an amplitude-limiter device with afrequency-demodulator for converting frequency-deviations from a centrefrequency of received carrier waves into corresponding output voltagesupona modulation-impedance, and modulator-devices of this invention foreffecting amplitude-limitation and phase-regeneration in the demodulatornetwork, for augmenting the conversion sensitivity of the demodulator.

Fig. 4 illustrates in graph form certain quantitative relationshipsshowing equilibrium of alternating currents of the generator networks,and determination of amplitudes of these alternating currents inrelation to the dynamic characteristic of the generator, the oscillationsustaining feedback voltage characteristic, and the negativebias-voltage determined characteristic of sinusoidal degenerativefeed-back voltage; also a modulating voltage modulating the negativebiasvoltage, and corresponding modulation of amplitudes of thealternating currents of the generator.

Fig. 5, illustrates a sinusoidal voltage impressed upon the modulatorcircuit by coupling with a network to be controlled by thediode-modulator of this invention, and also illustrates themodifications effected in the time of duration and the net voltage ofthe impulse, available for energizing the energy-storage facilities ofthe modulator circuit, and in relation to modifications of the negativebias-voltage upon a diode-anode. Y Fig. 6 shows a'graph of aconventional demodulator characteristic for convertingfrequency-deviations into illustrates theprocess of phase-regenerationfor increasing the resultant output-voltage of the frequency-demodulatorin relation to the amount of' frequency-deviation of impressed carrierwaves. a

An important feature of this invention, is the employment of impulseexcitation in thermionic diode circuitshaving predominant energy storageor reactance characteristics, and the determination of the energizationof these circuits from communication networks to be controlled, bycontrolling threshold magnitudes of negative biasvoltage upon one ormorediode-anodes, determining available voltage excess of energizing pulseabove threshold magnitude, and time of duration of pulse, and inrelation to natural period of oscillation of the energy storage circuit;also the modification of currents in the communication network to' becontrolled, byemployment of threshold-determined sinusoidal voltagewaves derived from oscillations in said energy storage facilities, forsuperposition upon grid control means of a thermionic amplifying meanscoupled with the communication network; andalternatively, by directreaction in the communication output-voltages, and

network for modifying reactance of the network directly, withoutintervention of the thermionic amplifying means, when the energy storagefacilities of the diode circuits or impulse-excited at frequencies farremoved from a natural frequency of said storage facilities.

These features, and others, are hereinafter pointed out in furtherdetail, and in connection with the structures of this inventionillustrated in the drawings. 7 Referring to the drawings, at 13 is athermionic tube, having the cathode 2, anode H, suppressorgrid i6,screen grid I5, and control-grid It. At i, in thermionic tube I3, is adiode-anode, forming a diode with cathode 2. At 30 is a source of Yunidirectional voltage for energizing anode ll,

and having its negative terminal connected to ground I8; the source 30serves also to supply a positive potential to screen-grid l5.Suppressorgrid i6 is connected directly to the cathode 2, at the cathodeterminal 20,. By-pass condenser 28 connected across source 30, serves tocarry alternating currents from anode ll around the source 30; alsoby-pass condenser 31 connected between screcngrid l5'and ground l8,serves to by-pass alternating currents from screen-grid I5 around source30, the impedance of condensers 28 and 3! being negligible in relationto other impedances of the circuits. The cathode terminal 2a isconnected to ground l8, through resistance 4, for example by thevariable contactor 8, and biasvoltage is established upon resistance 4in a manner well understood, by passage of the steady component ofcurrent from anode ii to cathode 2 through resistance 4, points uponresistance 4 having a negative bias-voltage relative to the terminal 20.of the cathode. A1525 is an inductance coil, tuned by the variablecondenser 26 which is shunted across the coil 25. At 12 is a bypasscondenser connected from terminal 2a to variable contactor 8, forpassing alternating currents around resistance 4. I

Referring to Fig. 1, a thermionic alternating current generator isshown, one terminal of the coil 25 being connected directly to the anodeH, the other terminal of coil 25 being connected "through thephase-balancing condenser 21 and phase-balancing resistance 29 tovariable. contactor l9, upon'resistance 4. An intermediate junction 1cupon coil 25, is connected through conductor G to the positive terminalof source 30. Inductively coupled with 0011 25, is the inductancc coil3,. one terminal of which is connected through the terminals 9 and ID,to ground i8, the terminal [0 being connected directly to ground l8. AtII is a modulationvoltage generator connected between the terminals 9and II]; when the modulation generator i I is not used, or whenmodulation voltages are not impressed between terminals 9 and Hi, thelatter terminals are understood to be conductively connected together bya negligible impedance. The other terminal of coil 3 is connected todiode-anode l, through the conductive circuit between terminals a and b.Connected between the terminals a and b, is a highly reactive circuit,capable of absorbing the major portion of the energy transferredimpulsively to the diode circuit 56 having a highreactance resistanceratio,

Coupled with the coil 6' inductively, is the indu tance .11 I, connectedbetween t e t m na ca d d ontrolr d ill is. connected to, tennis nel c.oic i and terminal d 0i c il l is eon-j netted to variable ccntactor 32upon r t n at 129 s. a -11 1 conde se or ne i ible impe ance. connectedbet n the var able con.- tactor l li and the cathode terminal 2a..

-..II.1.0rder, to better understand the operation of certain aspects ofthe structure of Fig. 1 of this invention, reference may next be made toFig, 5., and to Fig. 4;. In Fig. 1, when the coil 3 is une coupled fromcoil 25, and terminals 0 and (1 shortcircuitcd. by a conductor ofnegligible impedance, a'conventional form of thermionic alternatingcurrent generator exists, with phase-balancing means, and means foradjusting both the negative-bias-voltage and the oscillation-sustainingalternating fed-back voltage upon the controlgrid, [4. Means haveheretofore been provided for phase-balancing thermionic alternatingcurrent generators to reduce. the well known inconstancy of generatedfrequency of such generators; such phase-balancing is premised upon asingle simple harmonic frequency, which condition does not exist whenthe oscillatory currents are allowed to reach their equilibriummagnitude in the conventional manner. Thus, for example in the generator of- Fig. 1, a small reactance ma be introduced by the variablecondenser 21, together With the high resistance 29, to shift the phaseof the oscillation-sustaining or regenerative voltage upon thecontrol-grid I4, between [4 and cathode terminal 2a, and by a smallphase-angle sufficient tomaintain the regenerative voltage in exactphase-opposition to the vector sum of the voltage across the externalimpedance, e. g. between cathode 2 and anode I 1, and the voltage dropinternally, through the impedance of the thermionic tube between cathode2 and anode l1, and at the natural, undamped frequency of oscillation ofthe resonant system. Such a phase-balance provides improvement offrequency-stability in reference to random changes in thermionic tuberesistance between cathode 2 and anode l1; and so far as the fundamentalnatural frequency alone is concerned; other means for accomplishingsuchphase-balancing with reference to a, simple harmonic natural frequencyare known, for example Method and means for normalizing thermionicoscillators, U, S, Patent No. 2,305,362 of the present inventor, andwherein the above-. indicated phase-balance is effected to, avoid thenecessity of the oscillator to shift frequency to t li a e u i rium. wen thet ibe esist-- ance' or" oscillatory circuit resistances are modiefled Such phase-balancing is limited in effectiveness by the fact that asimple harmonic generatedfrequency does not exist, when the generatoralternating current is. allowed to reach its equilibrium magnitude in.the conventional'manr ner; harmonics are present in varying degrees,which'limit the effectiveness, of the above-described phase-balance forstabilizing the, generated frequency. The present invention provides,v

simple 'means for limiting the generated frequency to a single frequencyby threshold-limit-, ing of alternating grid-cathode voltages to any desr d me ium. as l si dula th mplitudes of the single generated frequency.

Referring to Fig, 5, at 6Q is ShOWn. a, sinusoidal VQltage e f mplitu eL nd. w th r erence to the time axis indicated by 53. At 62 is inditedel 'e d fi i a e at v b asol on e di n e i elativet q tli ee 2, a seforexam'pleby the variable contactor 8. The

voltage 6D represents a, voltage setup in coil 3 by inductive couplingwith the coil 25, and'the shaded portion 6i indicates instantaneousvalues of excess of positive voltage E +6410, abovea'n'egae tivebiasevoltage of magnitude edo. The-timeof a half-cycle of the voltage ofmaximum value E, is indicated by /2, and the time of duration of thepositive voltage impulse upon the diode-anode l as modified by thenegative bias-.voltage isin dicated by 1-. When the condenser 5 withinductance coil 6 is tuned to the fundamental gen-. erated frequency ofthe currents in the oscilla tory circuit 25-:26 of the thermionicalternating current generator, the tuned circuit 5-45 receives anenergizing pulse once every cycle. The circuit 5-7.6, .Fig. 1, has ahigh reactance-resistance ratio; the effective resistance between theterminals a and b is high in relation to the resistance of the diodel-2, and the major portion of voltage drop ofthe diode circuit is uponthe circuit ab. Also, the decrement of the oscillatory circuit 5i 5 isthen Very small, and substantially constant amplitude is maintained forthe alternating voltage between terminals a and b, and during the timebetween energy impulses. The alternating voltage upon the coil 6 is thusmodified in relation to amounts of negative bias voltage edg andcorrespondingly modified threshold-determined sinusoidal voltages areset up in the coil 7, no sinusoidal voltage beingdeveloped in the coil 1until the voltage E exceeds the adjustable negative bias-voltage cs0.Alternating voltages are thus developed across the terminals a'b, and inproperphase relationship, by means of a highly reactive network, toprovide degenerative voltages with respect to the regenerative o'oscillation-sustaining voltages upon the resistance 29, thesedegenerative voltages being threshold-de tor-mined. An important featureof this inven tion is the provision of means for producing thresholdcontrolled sinusoidal voltages, as dis,- tinguished from thresholdcontrolled voltages having harmonics, as for example when the highlyreactive circuit between terminals c and b is replaced by a highresistance; in this latter case only bias-excess'port-ions of sine wavesare trans,- mitted upon the high resistancebetween termi; nals a, and b,for degenerative purposes, or'for voltage limiting purposes. Re ring toFig. 4, :1 s, ndi a ed a dynamic characteristic of a thermionic,alternating current amplifier, showing a, typical relationship, betweenthe effective values of a1,t.ern atin,g v,olt-. age impressed upon acontrol-grid, e. g; grid M, and alternating currents between cathode andanode, with an external impedance, e. g, as, in Fig. 1, when separatelyexcited, At {5J5 indicated; an oscillation-sustaining feed-beck voltagechar-e. acteristic, showing the feed-back voltage avail.-.-. able forany particular cathode-anode alternatn current inv ela n. to the alteratin vo ta e required for sai current, as. indi ated by the,characteristic 6]. At 6.8, is indicated an equilibri um value ofalternating current of the alternating current generator, determined byequality of the, required and available. alternating volta es, invconventional forms, of thermionic alternating ur ent enerat s T echaacte i has a straight-line relationship between. impressed al ternatingvoltage and resultant cathodeeanode;

current through large negative grid voltages, and other causes. Animportant feature of the present invention is the'means for introducingdegenerative sinusoidal voltages, after a selective magnitude' ofalternating. voltage upon the controlrid is reached.

At 10 is indicated a characteristic of degenerativefeed-back, showingthe alternating voltage for opposing the regenerative feed-backvoltages, and in relation'to cathode-anode alternating currents. betweenZn-41. Thus at the particular alternating current indicated by the pointI3, the degenerative feed-back voltage is zero; this particularthreshold magnitude being determined by the fact that the specificnegative bias-voltage indicated by edo is sufiicient to prevent impulseexcitation of the resonator circuit -6. As greater alternating voltagesare impressed upon the coil 3, degenerative voltages appear across theterminals cd, and inrelation to increasing alternating currents betweencathode 2 and anode H, as indicated along the axis of ordinates;alternatingcurrents between cathode 2 and anode 11 being indicated byIp, and alternating voltages upon grid l4 being indicated by Eg, alongthe axis of abscissasc Thus for the specific alternating currentindicated by 76, if the grid M were separately excited, an alternatingvoltage corresponding to the-abscissa oi the point 74 would be requiredupon grid l4, whereas the feed-back voltage available with this current,and for sustaining oscillations, is indicated by E the degenerativevoltage available is indicated by E" The resultant regenerative voltageis thus E'g-E"g, and equilibriumalternating current of the thermionicalternating current generator is determined therefore at the magnitudeindicated by the point 74 along the straight-line part of thecharacteristic 61', instead of at the point 68. If the negativebias-voltage is modified to an amount indicated by the line 18, for thediode-anode l, the degenerative-voltage characteristic is shifted to thelineH, and the equilibrium alternatingcurrent of the thermionicalternating currentgenerator, is shifted to the magnitude indicated bythe point 71. At 19, is indicated a graph of modulating voltage upon thediode-anode I, in relation to time, the modulating voltages beingindicated at any instant by ed, superposed upon the set negativebias-voltage Gale, and such that the maximum positive value of ca doesnot exceed the value of the set negative bias-voltage edo. The resultantbias-voltage upon the diode-anode l is thus always negative, andmodified in relation to the passage of time. At 19' is indicated thecorresponding graph of'the envelope of the highfrequency sinusoidalcurrent waves of the thermionic generator, showing theamplitude-modulation of these currentwaves in response to modifiednegative bias-voltages upon the diode 1.

Thus, the circuit of Fig. 1, can be employed for frequency-stabilizationalone, or also for amplitude-modulation of the alternating currents; inthe former instance the terminals 9-l 0 are joined by a conductor havingbut small impedance in relation to the impedance of the diode connectedcircuit, and in the latter instance this conductor is omitted, theconductive circuit being completed through the source II for providingmodulation voltages across the terminalsQQ-IO, to modulate a resultantnegative bias-voltage upon the diodeanode I. The frequencies of themodulation voltages are understood to be lessthan the frequenciesgenerated by the thermionic alternating current generator. l

With reference to the employment of Fig. i forfrequency-stabilization,it will be noted-that the generated alternatingcurrents are limited to simple harmonic alternating currents of singleselectable frequency, providing the facility for precise'adjustment ofphase of the regenerative feed-back voltage by condenser 21, or othermeans previously referred to herein; likewise the threshold-determinedalternating degenerative voltages impressed upon the control-grid Maremaintained in substantial phase-opposition to the regenerative voltages,through control of phaseangle of the diode-connected circuit, e. g. byratio of reactance of coil 3 to reactance'and resistance of, thecircuit'between the terminals a andb. Other phase-determining networksfor impulse excitation, may be employed between the terminals (2-42, andc-d, in a manner well understood; for example quadrature-phase voltagesmaybe obtained across the terminals c-d by tuning the coil 7, or byother well known circuit means.

The operation of the grid-voltage amplitudelimiting structure of Fig.3is similar to that-described for Fig; 1, in reference to Figs. 4 and 5;in this instance the degenerative alternating voltage between thevterminals 0 and (1 increases at nearly the same rate with increase ofcathodeanode alternating current between I! and 2, above the thresholdmagnitude of alternating input voltage upon control-grid l4, astheimpressed alternating input voltage increases in relation to thisalternating current which it produces. Thus the effect of any increasein alternating input voltage upon the grid Hi is annulled, the thresholdmagnitude beyond which increases in input alternating voltage produce nofurther increase in the output voltage, being selectively determined bythe variable contactor 8'. Such amplitudelimitation is useful inreceivers for virequencymodulated carrier-waves, and the structure ofFig. 3 provides both selector means for controlling the limited voltagaand means for providing amplitude-limited sinusoidal waves asdistinguished from distorted or irregular shaped waves of constantamplitude,

Referring to Fig. 2, a'thermionicalternating current generator isillustrated; with thermionic tube l3a having anode Ha connected to oneterminal of coil 25, the other terminal of coil 25 being connected tothe resistance 4, through the variable condenser 21' in series withresistance 29; one terminal of resistance 29 is connected to thevariablecontactor 19 upon resistance 4, and the otherterminal of resistance 29is connected to the control-grid I la of tube 13 a. With cathode 2, arethe respective diode-anodes l and la, each providing with cathode 2 aseparate diode. Resistance 4 is connected from cathode terminal 211 tothe ground 18, through variable contactor 8 upon resistance 4. Coils 3and 3' are inductively coupled with the coil 25; these coils have equalself-inductance, and are connected in series at the junction 2 It willbe understood that a single coil may be used for coils 3 and 3', withthe junction 10' at the half-inductance point upon the single coil.Connected between the diode-anode l and the terminal of coil 3- oppositejunction 11',

" -2, and likewise the Combined series reactanc'e of coils 6d and 3' islarge in relation to there'sistarm of diode I'd-2, the circuitscontaining substantially pure inductive-reactance. Connected between thejunction p and the terminal 9,- is the conductor 1/. The terminal 9 isconnected to ground i8, through the modulation-impedance connectedbetween the terminals 9 and Ill, having the conductive path through theequal resistances 55an'd 53, in series, terminal It being connected toground l8. At 90 is illustrated in block-diagram form a conventionaldemodulator, connected to the modulation-impedance between terminals ,9and it is understood for the purposes of this invention that modulationvoltages are provided between the terminals 9 and I0. Thus for examplewith a conventional frequency-demodu: lator having frequency-modulatedcarrier waves impressed upon the input-terminals i and i,amplitude-modulated voltages are made available upon amodulation-impedance connected between the terminals 9 and I0,proportional to the amounts of frequency-deviation of the carrier waves,in a manner well understood. Such a conventional form offrequency-demodulator is further illustrated in Fig. 3, in detail. Theimpedance between terminals 9 and lil for frequencies of the thermionicgenerator, is understood to be negligible in relation to the rea-ctanceof the diode circuits, between diode-anode i and junction- 12, andbetween diode-anode la and junction p, because of by-pass condensers and52, respectively across the resistances 53 and 55, and the frequenciesof the modulation voltages across 9 and In to be low in relation to thefrequencies of the thermionic alternating current generator.

Operation of the diode modulator of the structure, Fig. 2', forutilizingthreshold-controlled impulse-excitation of the highly reactivediode circuitsto modulate the generated frequency ofthe thermionicalternating current generator, may be understood from the followingconsiderations. Without any modulating voltage present between terminals9 and Hi, the negative bias-voltage upon diode-anodes l arid la iscontrolled b the contactor 8 upon resistance 4; if this bias-voltage isset to zero, by contactor '8, then afull half-cycle voltage impulse incoil 3 from coil 25, is opera tive, and'likewise a full half-cycleimpulse in coil 3 from coil 25, is operative a half-period later. tosupply a current pulse through the'highl'y reactive diode circuit. Whennegative bias-Voltage is introduced by way of contactor 23, the durationof the voltage pulse effective for determining a current pulse, isreduced, and likewise the cited tive magnitude of the voltage pulseis'reduced, resulting in reduced alternating currents in the coils 3 3with the same induced voltage in 3-33 from coil 25, and in an increaseof the effective reactance of the diode circuits.

''In the structures heretofore disclosed herein, direct reaction of thediode circuit in the network to be controlled has been negligible, onlysufiic'ierit coupling-being necessary to set up control voltages forcontrolling a grid of a thermionic tube coupled with the netw'ork'to becontrolled: in the present structure however, no grid connection isemployed with the diode-modulator, directly. The diode circuits 2l2-l8-525|-p'3- la-2, are substantially purely reactive circuits, andare sufficiently tightly coupled inductively with the coil 25 to modifythe resultant reactance of coil 25 at the frequencies of thealternating' current thermionic ge erator. From'well known relations forsuch coupled circuits, if the inductance of coil'25f alone is designatedby L'zs, the mutual inductance between coil 25 and the diode circuitcoils 3; 3; by M, and thetotal selfinductance of either diode circuittym he resultantself-inductance of the'coil 25 coupled with the diodeinductance is: 1

i L 2s ='L25M /L (1) Wheniiiodification of the currents through inducta-e In is not effected by a negatively biased thermionic diode. When:modification of the inductance L0 is effected 'bycontrolling" the"resultant negative bias=vo1tage upon'the'dio'de anodes, it can readilybe shown that instead of L0, the resultant self inductaiice' of thediode-circuits is of the form: i

1 it? As employed in Fig. 2 for frequency-modulation, an initlalrieg'ative bias-voltage can, is set upon the resistance 4 by thecontactor 8. In Equation 2 the parameter a is defined by the ratioof theresultant negative bias-:voltage upon the diode anodes to thevoltageEr'set up in either coil 3 or coil 3', from coll25. When both positiveand negative modulating: Voltages are employed upon themodulation-impedance. as for example when the modulationdmpedance. isconnected to the output side of a frequency-demodulator, the neg ativebias voltage set at the contactor 8 is such as to be alway's'greaterthan the maximum positive voltage upon the modulation impedance, betweenterminals 9 and ,lll, so'that' the resultant bias-voltage upon thediode-anodes l and la is always negative.

Referring to Fig. 3, the diode-modulator devices of this invention areshown in connection witha frequency-demodulator, for providing amplitudelimitation of input-Voltages upon the demoduia tor and for providingphase regeneration in the demodulator circuit, to' largely increase theratio of output-voltage of the demodulator in relation to the amount offrequency deviation' of the frequency' modulated input voltages.Connected with the anode ll of tube I3, is a; conventional formoffrequency-demodulator circuit, one ter minal of coil 25 being connectedto anode ii, and the other terminal of coil 25 being connected to thepositive terminal of source it; Condenser 26 is shunted across coil 25.At 55 is a secondary coil, coupled with coil 25 inductivelyshuntedacross coil 56 is the condenser 4|. At 42 is a thermionictube,'havingdiode-cathode it with diode-'anodefi'd, and diode-cathode 45with diode anode 41. Conn'ectedbetweenterminals 9 and Ill, is theresistance 53 in series Withthe resist since 55, these resistances beingequal. shunted across resistance 53 is condenser 51, and shunted acrossr'esi'stanc'e" 55' is condenser 52. Terminal 9 is connected to diodecathode 1 5,; and terminal I i is connected to diode-cathode 46.Choke-coil All is connected between V the half-inductance junction 7'upon coil '56- arid the junction q between resistances 53 and 55.Connected between the anode ll. and the junction 9', is thelow-impedance condenser 43. ,The circuit. described, and; con-. nectedwith the anode I'l, comprises a conventional type of frequencydemodulator. The improvements effected by the diode-modulators of thisinvention, will be evident from the following details. At 2' and i :are:input terminals, inductivel-ycoupled withthe coil 25d, and condenser 1126a is shunted across the coil 2 5a. Cathode 2 or tube l3, has thediode-anode l, and the diodeanode la. Resistance 4 is connected betweencathode terminal 2a. and ground l8, through variable contactor 8.Connected between diodeanode la and variable contactor 8 upon resistance4, is the coil 3' in series with the terminals n 1); coil 6 is connectedbetween terminals a. and b, condenser 5 is shunted across coil 6, andcoil 3 is inductively coupled with coil 25. By pass condenser isconnected between contactor 8'- and cathode-terminal 2a. One terminal ofcoil a is connected to control-grid l4, and the other terminal of coil25a is connected to variable contactor [9 upon resistance 4, through theterminals o-d, the coil 1 being connected between the terminals 0 and d,and coupled with the coil 6. By-pass condenser H1) is connected betweenthe contactor l9 and cathode-terminal 2a, and Joy-pass condenser I211,is connected between oontactors l9 and 8. Suppressor-grid i6 isconnected to cathode-terminal 2a, and screengrid I5 is connected throughconductor a to a positive potential upon source 30. The abovedescribedmodulator device with cathode 2 and diode-anode la, provides a voltagelimiting device,

selectively limiting the amplitudes impressed upon thefrequency-demodulator.

Diode-modulator device including diode-anode l with cathode 2, providesphase-regeneration in the demodulator circuit, whereby voltagesestablished across the modulatiomimpedance between the terminals =9ill,of the irequency-demodulator, and responsive to the amount offrequencydeviation of the carrier waves from a centrefrequency, throughchanges in phase of voltages upon the demodulator circuit,-are employedto further modify such changes in phase to increase the conversionsensitivity of the demodulator for converting frequency-deviations toout put voltage between terminals 9-H). Diodeanode lis connected throughthe high reactance coil 60 and coil 3 in series, through conductor 48 tothe terminal 9 upon the modulationimpedance, the coil 3 beinginductively coupled with the demodulator network. Variable contactor I9serves to adjust the negative biasvoltage upon grid l4, variablecontactor 8' serves to adjust the negative bias-voltage upon diodeanodela for impulse-excitation of the circuit between terminals a--b, andvariable contactor 8 serves to adjust the negative bias-voltage on thediode-anode I, through the circuit 2--4-8l8lll-9483-6cl2, forimpulse-excitation of the reactance coils 6c and 3. The operation of thediode-modulator in modifying a resultant inductive reactance of acoupled network, has been described with reference to Fig. 2. Withoutphase-regeneration, an incremental change in resultant reactance isefl'ected in the demodulator network by a change in frequency, that is,by a frequency-deviation from the centre carrier frequency; thus if thisincremental reactance change is indicated by AX, then:

AX=41rLAf (3) in which A is the incremental frequency change, orfrequency-deviation, and L the inductance determining differentialoutput-voltage upon the modulation-impedance between terminals 9l0-.Referring to Fig. 6, at 9! is shown a typical graph relatingfrequency-deviation to output-voltage upon the modulation-impedance, forconven tional forms of frequency-demodulators, the output-voltageindicated by ea being of opposite polarity for positivefrequency-deviations in relation to the polarity for negativefrequencydeviations. At AX, is indicated an additional change ofreactance of the inductance L,,established by the diode-modulatorincluding the diode-anode I; The regenerative phase-amplification thusestablished will -be apparent from Fig. 6. Due to modification of theinductance L, by the amount AL, through action of the modulator-device,there is a further change of reactance of wherein J'c is thecentre-frequency of the carrier waves, and AL change of inductanceeffected, in the equilibrium condition. At P is indicated thephase-reflex line, relating reactance change available throughphase-regeneration, for any particular modulation-voltage ed, betweenthe terminals El-l0; at 9| is indicated the line relating reactancechange required to produce the particular voltage ed, byfrequency-modulation alone, the frequency-deviations being measuredalong the axis of abscissas, 92. Thus at the equilibrium point indicatedby B, the total reactance change is indicated by AX-l-AX', of which onlythe amount AX is established by frequency-deviations, directly, and theresultant output-voltage between the terminals 9-I0 is indicated by theordinate at B, instead of by the normal output-voltage indicated by theordinate at B. The resultant phase-regenerative amplification of theoutput-voltages is thus seen to be defined by the ratio:

in which D is the slope of the demodulator characteristic, and D' theslope of the phase-reflex line P, and D is greater than D.

It will be understood, that the polarity of modulating voltage appliedto the diode-modulator from terminals il-10, in relation tofrequency-deviation, is such as'to augment the conversion sensitivity.the polarity being selective; also that the scope of this invention isnot limited to employment of phase-regeneration in the specificfrequency-demodulator here illustrated, there being other forms offrequency-demodulators employing phase-shift to determineoutputvoltages, for example, Thermionic device for convertingfrequency-modulation into amplitudemodulation, U. 8. Patent No.2,369,055, February 6, 1945, of the present inventor. It will likewisebe evident that when the opposite polarity is selected, the modificationof tuning of the demodulator network is in the opposite sense, to-

- ward a tuned condition instead of toward increase ofde-tuning.

Referring to the principal object of this invention, it will beunderstood that a super-heterodyne receiver may employ thediode-modulator devices of this invention for automatic adjustment oftuning of the demodulator to intermediate-frequency, or forphase-regeneration in the demodulator, and that the demodulator mayinclude a diode-modulator device for limiting the amplitudes, whenreceiving frequency-modulated carrier waves. The mixer orfrequency-reducer of the super-heterodyne is understood to have athermionic alternating current generator, for example as describedherein, and containing a diode-modulator as described, for modifying thefrequency of the generator, without the necessity of a separatereactance-modulator tube.

Operation of the diode modulated device of this 1-3 invention as awave-synthesizer will first be described with reference to the simplestemployment of the device, for controlling the functional relationshipbetween the amplitudes of impressed sinusoidal waves e. g. upon coil 25,Fig. 3, and the amplitudes of sinusoidal output-voltages e. g. at theterminals c-d, Fig. 3. It will be understood that more than one diodemodulator may be energized from coil 25, and independently biased bymeans of a variable contactor such as 8' upon resistance 4. either inphase-conjunction, or phase-opposition, or combinations of these, areemployed in the circuit connecting the output terminals such as c-d.Thus, as the amplitudes of the impressed voltage across coil 25 areincreased, the amplitudes of the output-voltages may be controlled toconform to various functional relationships; a, few examples willillustrate the synthesis of relative Wave amplitudes.

It will be evident that the negative bias-voltages can be spaced so thatthe various impulse-excited circuits contribute-to the totaloutput-voltage in a sequence, as the impressed voltage increasessufficiently to exceed the threshold values. Thus, increments to theoutput-voltage can be supplied in a sequence, so that the output-voltagein the circuit connecting the output-terminals such as c-d increases inrelation to the input-voltage in a relation approximating the N-th powerof the input-voltage, N being greater than unity. Or, alternatively, alldegenerative or phase-opposing voltages can be introduced in sequenceinto the circuit connecting said terminals, to approximate the N-thpower relation, N being fractional. Or alternatively, combinations ofthreshold con trolled phase-aiding and phase-opposing voltages can beused, providing output-voltage characteristics which are concavedownward for a range,

and then concave upward, or alternatively, 0011- a cave upward for arange and then concave downward. Other functional relations will beapparent, and in relation to the multiplicity of diode modulatorcircuits employed.

An important feature of the functional relations so evolved, is thefacility for providing nonlinear relationships between impressed andoutput-voltages, without the necessity of distortion of the outputwave-shape, as in the case of conventional forms of transmission throughnonlinear conductors; in the above process sinusoidalthreshold-controlled incremental or decremental voltages are employed,providing a sinusoidal resultant.

Many threshold-determined phase-shift relationships may be evolved; asingle illustration will suffice. When one of the impulse-excitedtransfer circuits provides the facility for introducingquadrature-voltage components, as heretofore described, Ithreshold-determined phase-shifts are obtainable. For example, with asingle diode-- anode device, e. g. with diode-anode la, a sinusoidalresultant voltage can be made to increase linearly with theinput-voltage until a set magni tude is reached, after which theresultant voltage begins to shift phase relative to the input-voltage.

In the employments of impulse-excitation described, the tuned transfercircuits have been tuned to the frequency of excitation impressed I uponthe modulator circuits, that is, when the In this usage, thresholdvoltages nected with the oscillatory transfer circuit. Excitation of atransfer circuit having tunable oscillatory facilities as illustrated,may however, be effected for maintaining alternating currents in thetransfer circuit by furnishing energy impulses less frequently than oneper cycle of natural oscillations of the transfer circuit. Thus, if thetransfer circuit is tuned for twice the frequency of the impressedvoltage upon the diode-modulator, energy impulses can'be furnishedto'the transfer circuit of duration equal to, or less than, the time ofone half-cycle of the double frequency, as illustrated in Fig. 5 showingduration 1- and magnitude of positive pulse upon a diodeanode, inrelation to negative bias-voltage upon the diode-anode, and to thevoltage impressed upon the diode circuit. Similarly, when theoscillatory transfer circuits are tuned for multiple frequencies of thefrequency impressed upon the diode-modulator circuit, multiple frequencyalternating currents can be maintained in the transfer circuits, throughnegative bias-voltage control of the time T" of impulse excitation. Whenan alternating voltage of frequency F is impressed upon the circuit2526, output-voltages can thus be made available at the output terminalssuch as c--d, with harmonic frequencies selectively controlled as toamplitude and phase.

In the diode-modulators herein'described, coupling for supplyingimpulsee'xcitation has been illustrated between the diode-circuit andthe output-impedance of a thermionic amplifier; it will be evident thatthis coupling can alternately be with the input-impedance, and likewisethe impulse-excited resonator coupled with the inputimpedance forcombining alternating voltages from the input-impedance withthreshold-controlled alternating voltages from the resonator reactancenetwork, 0. g. for application of the combined voltages between the gridand-cathode of a thermionic tube, for effectingcontrols heretoforedescribed, herein. Coupling with the output-impedance affords largeravailablevoltages for impulse-excitation, and correspondingly largerthreshold-controlled alternating voltages.

Having described severalillustrative embodiments of my invention, it wil be evident that changes can be made in the form and arrangement ofparts, and by substitution in part ofother well known structures, orotherwise, without departing from the spirit of my invention, and I donot therefore limit the scope of the invention to such particularembodiments.

What is claimed is:

1. In a thermionic amplifier having a thermionic tube with cathode,anode, and grid, an input-impedance connected to saidgrid and to saidcathode, and an output-impedance connected to said cathode and to saidanode, a diode-modw lator device for controlling phase and magnitude ofalternating currents in said output-impedance,

said device having a thermionic diode means in-' eluding a diode-anodewith said cathode, a diodecircuit connected between said diode-anode andcathode, including connections serially through a I negativebias-voltage control means for controlcontrolling phase and magnitude ofvoltages upon said input-impedance.

2. In combination with the structure of claim 1, a third coupling meanscoupling said outputimpedance with said input-impedance for generatingsaid alternating currents, a modulationimpedance in series with saiddiode-circuit, and modulating-voltage means connected with saidmodulation-impedance, for varying the resultant negative bias-voltageupon said diode-anode, to modulate said alternating currents.

3. A diode-modulator device for modulating alternating currentamplitudes, in an alternating current thermionic generator having athermionic tube with cathode, anode and grid, an inputimpedanceconnected between said cathode and grid, .an output-impedance connectedbetween said cathode and anode, and a coupling means coupling saidinput-impedance with said outputimpedance, said device having athermionic diode means including a diode-anode with said cathode, acircuit connected between said diode-anode and cathode includingconnections through a negative bias-voltage means for negatively biasingsaid diode-anode relative to said cathode, an inductance coil shunted bya condenser, tuned to said alternating currents, and amodulation-impedance; a first coupling means coupling said circuit withsaid output-impedance, a second coupling means coupling said inductancecoil with said input-impedance, impressing degenerative alternatingvoltages upon said input-impedance, and modulating-voltage meansconnected to said modulation-impedance, for varying the resultantnegative bias-voltage upon said diode-anode.

4. A diode-modulator device for modulating alternating currents in athermionic alternating current generator having a thermionic tube withcathode, anode, and grid, an input-impedance connected between said gridand cathode, an output-impedance connected between said cathode andanode, and a coupling means coupling said input-impedance with saidoutput-impedance, said device having a thermionic diode means includinga diode-anode with said cathode, a diodecircuit connected between saiddiode-anode and cathode serially including connections through anegative bias-voltage means for negatively biasing said diode-anode, atransfer-impedance including a resonator-circuit for controlling phaseor transferred voltages, and a modulation-impedance; a first couplingmeans coupling said diodecircuit with said output-impedance, a secondcoupling means coupling said transfer-impedance with saidinput-impedance, in quadrature with the voltages upon saidoutput-impedance, and modulating-voltage means connected to saidmodulation-impedance, for varying the resultant negative bias-voltageupon said diode-anode.

5. The combination with a thermionic amplifier having a thermionic tubewith a cathode, grid, and anode, an output-impedance connected betweensaid anode and cathode, and an inputimpedance connected between saidgrid and cathode, of a diode-modulator device for limiting alternatingvoltages upon saidoutput-impedance to a substantially constantmagnitude, independent of increases of alternating voltages upon saidinput-impedance beyond a selectable norm; said device having athermionic diode means including a diode-anode with said cathode, acircuit connected between said diode-anode and cathode includingconnections with a bias-voltage control means for controlling negativebiasing of. said diode-anode relative to said cathode, aresonatorcircuit means including an inductance coil shunted by acondenser, tuned by said condenser to said alternating voltages andcapable of free electrical oscillations of small decrement, and acoupling, impedance; 3, first coupling means coupling saidcoupling-impedance with one of said amplifier impedances, and a secondcoupling means coupling said resonator-circuit means with saidinput-impedance, impressing voltages upon said grid of opposite phase tosaid input voltages, when said input voltages exceed said norm,selectably determined by the magnitude of said negative bias-voltageupon said diode-anode,

6. The combination with a frequency-demodulator for convertingfrequency-modulated carrier currents to amplitude-modulatedoutput-voltages, of a diode-modulator device, for increasing theconversion sensitivity of said demodulator, said demodulator having aphase-shifting network determining said amplitude-modulatedoutputvoltages responsive to variations of frequency'of the carriercurrents, and an output-impedance for said amplitude-modulatedoutput-voltages, said device having a diode with diode-anode anddiode-cathode, a circuit between said diodeanode and diode-cathodevincluding connections with a negative bias-voltage control means forcontrolling negative biasing of said diode-anode relative to saiddiode-cathode, and an inductive impedance; a first coupling meanscoupling said inductive impedance with said phase-shifting network, anda second coupling means coupling said negative bias-voltage controlmeans with said output-impedance, for increasing the resultantphase-shift in said phase-shifting network initiated by a variation offrequency of said carrier currents.

7. A diode reactance-modulator device for modifying reactive alternatingvoltages in a phase-shifting network, said device having a thermionictube with a cathode and a diode-anode with said cathode, control-circuitmeans con-; nected between said cathode and diode-anode comprising anegative bias-voltage control means including a modulation-impedancemeans for controlling negative biasing of said diode-anode relative tosaid cathode, and an inductance coil means having large reactancerelative to the re-.

sistance between said cathode and diode-anode, to the inherentresistance of said coil means,-"and to said modulation-impedance means,said means being serially connected; inductive coupling means couplingsaid control-circuit means with said phase-shifting network for transferof energy, and voltage-control means connected with saidmodulation-impedance means for controlling the resultant negativebias-voltage upon said diode-anode, to control the stored energycontrol-circuit means.

8. In combination with the structure of claim 7, said thermionic tubehaving a second'anode' and a grid for controlling thermionic currentsbetween said cathode and said second anode, said phase-shifting networkbeing connected between connected to said anode and to said cathode, in?cluding connections with an energizing source for of said p l-s ri i islil hea h de: c m s n i A sto a mean sa d. w. l st n i ha t s ins tvsly.p sinels swana; s an all a jd Y a ,lating means connected -withsaid mogul v. impeclan ce for varying the ,.r,esu1tant .,n bias-voltageupon saiddiode anode.

Midg -gr d w t sa gtli sia.

eidla hosi i. an a us voltage upon said;diode angde oversaid negativebias-voltage; coupling means coupling said diode-circuit meanstransmitted am; is

with said network, and a. regulatin means reguat as magn u e o sai sesmebias-vo t 10. In combination with the structure of claim 9, amodulation impedam'ce connected in series withsaid diode-circuit means,and voltage-modu-' (11.- In Combination with the structure of. claim .9a 'secondcoupling meanscoupling saidj'dicdeinductance means withsaidinput-impe'clance'.

l2. In combination with the structure of claim 9, Tco ndenser meansconne ted-with said ,Tdiodeinductance means for tuningsaid arose-"arenameans, and a second coupling means coupling said diode-inductance meanswith said input-impedance.

13. In combination with the structure of claim 9, condenser means fortuning said diode-inductance means, a modulation-impedance connected inseries with said diode-circuit means, voltagemodulating means connectedwith said modulation-impedance for varying the resultant negativebias-voltage upon said diode-anode, and a second couplin means couplingsaid diode-inductance means with said input-impedance, for regulatingmagnitude and phase of alternating voltages upon said grid from saiddiode-circuit means.

14. In combination with the structure of claim 9, a second couplingmeans coupling said inputimpedance with said network for producingselfsustained alternating currents, condenser means for tuning saiddiode-inductance means, and a third coupling means coupling saiddiode-inductance means with said input-impedance, for regulatingmagnitude and phase of alternating voltages upon said grid from saiddiode-circuit means.

15. In combination with the structure of claim 9, a second couplingmeans coupling said inputimpedance with said network for providing selfsustained alternating currents, condenser means for tuning saiddiode-inductance means, a third coupling means coupling saiddiode-inductance means with said input-impedance, regulating phase andmagnitude of alternating voltages upon said grid from said diode-circuitmeans, a modulation-impedance connected in series with saiddiode-circuit means, and voltage-modulating means connected with saidmodulation-impedance for modifying the resultant negative bias-voltageupon said diode-anode.

16. The combination with a frequency-demodulator for convertingfrequency-modulated carrier currents into amplitude-modulatedoutputvoltages, of a phase-modulator device for modifying the specificamount of phase-shift in said demodulator for any constantfrequency-deviation of said impressed carrier currents, said dels1ai havn -g i a 9 1 tm' ianl v e output-voltages, said devic havin ,mean fa aia ua'mu e m ai g a an em amadr mam-J inginput-.voltage said .devicehaving. a, ,i en =si, qi i i 1 output impedance coupled said -1 tlase-shiftingnetwork and .l d

mcdulator means'includingabiasv mismpeaa ic with" said rea'c'tan meansfor. controlling said i r. sam is ages from an impl es ance' a 'diodehaving 'a cathode and 'a d deeanode with said cathode, a tuned t'ra fecapable of ire electrical 'QVSCI H e crement, having .input termin'als,

minals,v and a conductive athfbeti v putterminals, a bias-voltagecontrol In ing a positive terminal connected to said cathode, aconductive circuit between said diode-anode and a negative terminal uponsaid bias-voltage control means, including said conductive path throughsaid input-terminals of said transferimpedance and a conductive paththrough a diode-coupling means coupling said conductive circuit withsaid transfer-circuit for impulsively energizing saidtransfer-impedance; and the circuit means for combining voltages uponsaid transfer-circuit including said output-terminals of saidtransfer-impedance.

18. A modulator device for modifying alternating voltages upon anelectrical filter-circuit, said device having a diode means including acathode and a diode-anode, a diode circuit connected between saiddiode-anode and cathode including a tuned-reactance resonator meanscapable of free electrical oscillations of small decrement, a firstcoupling means coupling said diode circuit with said filter-circuit forimpulsively exciting resonance oscillations in said tuned-reactanceresonator means, a negative bias-voltage control means connected withsaid diode circuit for controlling amount of negative bias-voltage uponsaid diode-anode, and controlling impulse-excitation of saidtuned-reactance resonator means responsively with excess of positiveimpulse-voltage upon said diode-anode above said negative bias-voltage,and a second coupling means coupling said tuned-reactance resonatormeans with said filter-circuit, for combining impulse-excitedoscillatory voltages from said tuned-reactance resonator means withalternating voltages upon said filter-circuit, and for controlling thephase and magnitude of said combined voltages.

19. A diode reactance-modulator device for modifying reactive voltagesupon a phase-shifting network, said device having a diode rectifyingmeans including a diode-anode with a cathode, conductive diode-circuitmeans including said means, comprising predominant energy-storage meansconserving substantially all of any energyimpulse upon saiddiode-circuit means, including inductance means and a negativebias-voltage is name to said cathode, said means being serially con-"nected; energizing means for impulsively energizing said inductancemeansfrom energy of said phase shiiting network, responsively withexcess of positive voltage above said negative bias-voltage, includinginductive coupling means coupling said diode-circuit means with saidphase-shifting network,.and a second coupling means including 15a.thermionic'conductance means coupling said diode-circuit'means with saidphase-shifting networkfor reflex-control of voltages upon saidphase-shifting network.

20. In combination with the structure of claim '19,' resonator-meansincluding capacitance means coupled with said'inductance means fortuning with a frequency of said phase-shiftin network, 'for controllingthe phase of voltages upon said coupling means.

' 21;A diode modulator device for modifying voltages upon aphase-shifting network, said device having a diode-rectifying meansincluding a cathode'with a diode-anode, diode-circuit means connectedbetween said cathode and diode-anode serially including a resonatormeans'and a negative bias-voltage control means for controlling "theamount of negative bias-voltage of said diodeanode relative to saidcathode, said resonator 20 means being resonant with a frequency of saidnetwork; energizing means for impulsively sustainingosci'llations insaid resonator means with energy from "said phase-shifting networkresponsive to excess of positive voltage above said'negativebias-voltage, including a first coupling means coupling saiddiode-circuit means with said network, and a second coupling meansincluding a thermionic conductance means coupling said diode-circuitmeans with said phase-shifting network, -for reflex-control of the phaseand magnitude of voltages upon said network.

EDWARD H. LANGE;

REFERENCES CITED The following references'are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,948,169 Eremeef Feb. 20, 19342,128,993 Farhnam Sept. 6, 1938 2,161,406 Charrier June 6, 19392,248,197 Ra'th July 8, 1941 2,267,703 Henkler Dec. 23, 1941 2,296,921Green Sept. 29, ,1942 2,312,070 Bliss -g Feb; 23, 1943 2,362,898 Gilman'Nov .f14,.1944

